Optionally determining the null point in electronic selection circuits



all? 26, 1965 S. PETRY OPTIONALLY DETERMINING THE NULL POINT IN ELECTRONIC SELECTION CIRCUITS Filed Sept. 15. 1960 United States Patent 3,214,521 OPTIONALLY DETERMINING THE NULL POINT IN ELECTRONIC SELECTION CIRCUITS Sigmar Petry, Munich, Germany, assignor to Siemens &

Halske Aktiengesellschaft, Berlin and Munich, a corporation of Germany Filed Sept. 13, 1960, Ser. No. 55,701 Claims priority, application Germany, Sept. 17, 1959, s 64,947 5 Claims. (Cl. 17918) This invention is concerned with a circuit arrangement for optionally determining the null point in electronic selection circuits of the type such as disclosed in copending application Serial No. 722,357, filed March 18, 1958, now Patent No. 3,051,793, the rights in which are assigned to the assignee also named in the present case.

The copending application discloses various embodiments of electronic selection circuits cooperatively related to a plurality of operating devices, any number of which may be busy, each of said electronic circuits serving to mark in a defined sequence the first idle operating device by connecting thereto a predetermined potential which differs as to magnitude or polarity from the potentials connected to the remaining operating devices. The selection circuit is for this purpose subdivided into stages corresponding in number to the number of operating devices cooperating therewith. Each operating device conducts to its respectively associated stage a potential the magnitude or polarity of which is indicative of its momentary operation condition (busy or idle condition) and receives from the corresponding stage a potential for effecting the marking thereof when such marking is indicated. The connection and the delivery of these two potentials is effected respectively over the testing input and the marking output of the respective stages of the selection circuit.

A chain circuit which extends through the entire selection circuit is of decisive importance for the functioning thereof. This chain circuit comprises means contained in the respective individual stages, each such means being directional with respect to its transmission properties and being operative to connect a coupling input with a coupling output of its stage. Upon interconnection of the stages to form a selection circuit, the chain circuit will effect connection of the coupling input of each stage (excepting the first stage) with the coupling output of the respectively preceding stage. Each stage can in this manner influence over this chain circuit the respectively directly succeeding stage and over the latter all succeeding stages. This influencing can be explained in simplest manner by observing that the stage which first receives from its respectively associated operating device a potential indicating idle condition, briefly referred to herein as idle potential, gives off marking potential while preventing all succeeding stages from giving off marking potential. It will be seen, therefore, that the chain circuit is effective to produce unequivocal delivery of marking potential and to rnaintain at the same time a definite sequence or order of marking potential delivery.

The marking potential delivery proceeds always frorn the same null point so long as the chain circuit of the stages remains unaltered. This null point must be visualized to lie ahead of the stage the coupling input of which is left vacant, such stage being accordingly the first in the marking sequence. In order to change the marking sequence, which is desirable, for example, for placing the operating devices into operation substantially uniformly or the same number of times, the previously mentioned copending application proposes to cycle the original chain circuit by connecting the coupling input of the originally first stage with the coupling output of the originally last stage and to insert a contact always between two successive stages. Only one of these contacts is open at any time, thereby restoring the original chain circuit; however, the start of the chain circuit can now be optionally determined by opening a desired contact.

In the individual embodiments described in the previously noted copending application, the connection between the coupling input and the coupling output of each stage is formed by a transistor having its emitter connected with the coupling input and its collector with the coupling output. The transistor will be conducting when the coupling input receives release potential while the base thereof which is connected with the testing input, receives potential indicating busy condition, hereinafter referred to as busy potential. The transistor will in such case transmit the idle potential to the coupling output, thereby placing the respectively successive stage in a position to likewise deliver idle potential or to give off marking potential.

The object of the present invention is to eliminate the contacts for determining the null point, which are in many cases undesirable owing to the comparatively long time required for the operative actuation thereof, and to use in their place an electronic control which operates practically without inertia, while fully retaining the possi bilities afforded by stages in which the connection between the coupling input and the coupling output is effected by transistors. The switching stage according to the invention also provides an input for the connection of a potential for determining the null point, and means for connecting such input with the coupling output.

An embodiment of the invention will now be described with reference to the accompanying drawing to give an example.

The drawing shows a selection circuit having stages A, B N, each individual stage comprising a transistor T, in the illustrated case a pnp-transistor, which is disposed between the coupling input K1 and the coupling output K2 of the respective stages. The switching stages are for reasons of lucid representation shown in simplified manner which emphasizes the salient features. The construction of the individual switching stages may conform to any one of the embodiments of the copending application which comprises a transistor disposed between the coupling input and the coupling output. The functions of the switching stages are as such not altered by the measures applied according to the invention, and it is therefore and in view of the previous explanations as to the operations thereof, deemed unnecessary to enter into further details with respect thereto.

Each switching stage is provided with an auxiliary input 11. serving for the connection of the potential which determines the null point of the selection circuit. This input 12 is connected with the coupling output K2 over a diode G1. A further diode G2 is provided in a circuit extending from the auxiliary input n over a resistor to the base of the transistor T which is disposed between the coupling input 1 and the coupling output k2. The diodes G1 and G2 are polarized so that both will pass current when a potential is connected to the input n which is equal to the release potential conducted to the coupling input k1. All switching stages of the selection circuit are interconnected by circuit means extending between their respective coupling inputs k1 and coupling outputs k2 to form a cycling ring circuit. Testing inputs p and marking outputs z interconnect the respective stages with the operating devices respectively cooperating therewith.

In the case of the switching stages which are being considered in connection with the illustrated example, the release or idle potential is positive and the blocking or busy potential is accordingly negative. Both are to be considered with reference to an average value to be formed therefrom and therefore constitute relative values. A device which is schematically indicated at Sp delivers to the inputs n of all except one of the switching stages A, B N a negative potential which corresponds approximately to the blocking or busy potential of a coupling output, while delivering to the input 12 of one stage only a positive potential corresponding to the release or idle potential. This positive potential, which determines the null point, flows over the rectifier G1 to the coupling output k2 of the respective stage and thereby to the coupling input k1 of the respectively successive stage where it operates as a release potential for such stage. The connection of the release potential to the coupling input, which is independent of the function of the selection circuit, is in the arrangements under consideration typical for the switching stage which is with respect to the marking sequence in the first place. It follows, therefore, that the switching stage, the input n of which receives contrary to all other switching stages, positive potential, lies as the last one in the marking sequence.

In the marking of a device there arises a circuit which extends from the auxiliary input of that switching stage to which the potential establishing the null point is fed from the device Sp, over the rectifier G1 of such switching stage, the transistors T of following switching stages whose test inputs p receive busy potential, and the resistor R of that switching stage which is the first receiving idle po tential, and the user connected to its marking output 2.

The positive potential which determines the null point is thus directly connected to the coupling output k2 and and therewith to the collector of the respective transistor T. In order to reliably prevent actuation of this transistor over its collector into conducting condition, the positive potential which determines the null point is over rectifier G2 also connected to the base of this transistor which accordingly remains securely blocked. This blocking has no effect so far as the function of the selection circuit is concerned since the transistor, disposed between the coupling input k1 and the coupling output k2, has to conduct current only when release potential is to be connected to the succeeding switching stage, which never happens in the case of a switching stage lying in the marking sequence or order in the last place.

The schematically illustrated device Sp determines the null point by supplying appropriate potentials. This device, which may be constructed in most varied manner, has generally speaking merely the function of maintaining the place assumed by the null point incident to the last effected marking operation or the place to be assigned to the null point incident to the suceeding marking operation. The device is accordingly mainly a storer with a number of stages corresponding to the number of possible or desired null point positions. Such storer can be caused to step incident to each seizure operation or attempted seizure operation, and is for this purpose advantageously made in the form of a cycling or ring counting chain.

The selection operation takes place as soon as the device Sp conducts to one of the switching stages of the selection circuit the potential which determines the null point. In case this is not desired, blocking devices are connected ahead of the respective testing inputs p of all switching stages, such blocking devices making the connection of the idle potential only at a desired instant possible, or to construct the device Sp so that it effects in its normal condition merely preparatory storing of the null point position while releasing the potential which determines the null point only at the desired instant. The means required for efiecting corresponding operations are well known in the art.

Changes may be made within the scope and spirit of the appended claims which define what is believed to be new and desired to have protected by Letters Patent.

I claim:

1. In a signaling system having a selection circuit comprising a plurality of switching stages, each of said switching stages having first, a testing input for receiving a potential signifying idle or busy condition, second, a marking output for extending a potential signifying neutral condition or marking condition, third, a coupling input, and fourth, a coupling output for respectively receiving an extending potential signifying release or blocking, wherein means respectively connected on the input and on the output side to said coupling output comprises a transistor having a base, an emitter and a collector, in which the emitter is connected to the coupling input and the collector to the coupling output, the transistor being conductive only upon application of a release potential to the coupling input and a busy potential to the test input, the combination in which said switching stages are connected together to form a ring circuit in which the coupling input of each switching stage is directly coupled with the coupling output of the preceding switching stage, a storage device having storage stages corresponding in number to the number of switching stages, a single storage stage in each case delivering a potential which corresponds to the release potential, the stage of said storage device delivering such potential thereby determining the null point, means forming an auxiliary input for each switching stage, means for connecting the auxiliary input of each switching stage with the output of the corresponding storage stage, and a directional conducting element in each switching stage, which is connected between the coupling output and the auxiliary input, which element is conductive only when the potential corresponding to the release potential is fed to the auxiliary input from the corresponding stage of the storage device.

2. An arrangement according to claim 1, wherein said null point determining potential is supplied for initiating a marking operation.

3. An arrangement as set forth in claim 1, comprising means for connecting the base of said transistor with said auxiliary input for the application of a potential thereto which becomes effective over said element only responsive to the extension, to the auxiliary input, of said potential which determines the null point.

4. An arrangement according to claim 1, wherein said directional conducting element comprises a diode.

5. An arrangement according to claim 3, wherein said directional conducting element comprises a diode.

References Cited by the Examiner UNITED STATES PATENTS 2,906,891 9/59 Scanlon 30788.5 3,071,700 1/63 Smith 30788.5 3,081,405 3/63 Hovey et a1 307-885 3,089,961 5/63 Overn et al. 30788.5

ROBERT H. ROSE, Primary Examiner.

GEORGE WESTBY, JOHN W. HUCKERT, Examiners. 

1. IN A SIGNALING SYSTEM HAVING A SELECTION CIRCUIT COMPRISING A PLURALITY OF SWITCHING STAGES, EACH OF SAID SWITCHING STAGES HAVING FIRST, A TESTING INPUT FOR RECEIVING A POTENTIAL SIGNIFYING IDLE OR BUSY CONDITION, SECOND, A MARKING OUTPUT FOR EXTENDING A POTENTIAL SIGNIFYING NEUTRAL CONDITION OR MARKING CONDITION, THIRD, ACOUPLING INPUT, AND FOURTH, A COUPLING OUTPUT FOR RESPECTIVELY RECEIVING AN EXTENDING, POTENTIAL SIGNIFYING RELEASE OR BLOCKING, WHEREIN MEANS RESPECTIVELY CONNECTED ON THE INPUT AND ON THE OUTPUT SIDE TO SAID COUPLING OUTPUT COMPRISES A TRANSISTOR HAVING A BASE, AN EMITTER AND A COLLECTOR, IN WHICH THE EMITTER IS CONNECTED TO THE COUPLING INPUT AND THE COLLECTOR TO THE COUPLING OUTPUT, THE TRANSISTOR BEING CONDUCTIVE ONLY UPON APPLICATION OF A RELEASE POTENTIAL TO THE COUPLING INPUT AND A BUSY POTENTIAL TO THE TEST INPUT, THE COMBINATION IN WHICH SAID SWITCHING STAGES ARE CONNECTED TOGETHER TO FORM A RING CIRCUIT IN WHICH THE COUPLING INPUT OF EACH SWITCHING STAGE IS DIRECTLY COUPLED WITH THE COUPLING OUTPUT OF THE PRECEDING SWITCHING STAGE, A STORAGE DEVICE HAVING STORAGE STAGES CORRESPONDING IN NUMBER TO THE NUMBER OF SWITCHING STAGES, A SINGLE STORAGE STAGE IN 